Methanol plasma-catalytic oxidation over CeO2 catalysts: Effect of ceria morphology and reaction mechanism

Abstract The effect of CeO 2 morphology on efficient methanol oxidation and the detailed reaction mechanism were investigated in a plasma-catalytic system at room temperature. CeO 2 with different morphologies (i.e. rod, particle, and cube) were prepared by a hydrothermal method and characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), Raman and X-ray photoelectron spectroscopy (XPS). Among the three CeO 2 morphologies, CeO 2 rod catalyst had the most amount of oxygen vacancy. All the catalysts were tested for methanol oxidation in plasma, and the results showed that CeO 2 rod catalyst exhibited the highest methanol conversion (94.1%), CO 2 selectivity (90.1%) and ozone suppression. In situ Raman spectroscopy experiments proved that the performance of ozone decomposition was related to the amount of oxygen vacancy in CeO 2 . Surface oxygen vacancies in CeO 2 rod catalyst acted as active sites for ozone decomposition, resulting in more reactive oxygen species that could effectively oxidize methanol and increase CO 2 selectivity in the plasma-catalytic system. Finally, the evolution of adsorbed intermediate species and some key steps of methanol oxidation were discussed based on the results of plasma-catalytic in situ Fourier Transform Infrared Spectrometer (FTIR) experiments.